Thyroxine-binding globulin

SERPINA7
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 2CEO, 2RIV, 2RIW, 2XN3, 2XN5, 2XN6, 2XN7, 4X30, 4YIA
Identifiers
Aliases	SERPINA7, TBG, serpin family A member 7, Thyroxine-binding globulin，TBG, TBGQTL
External IDs	OMIM: 314200; MGI: 3041197; HomoloGene: 20113; GeneCards: SERPINA7; OMA:SERPINA7 - orthologs
Gene location (Human) Chr. X chromosome (human)[1] Band Xq22.3 Start 106,032,435 bp[1] End 106,038,727 bp[1]
Gene location (Mouse) Chr. X chromosome (mouse)[2] Band X|X F1 Start 137,980,006 bp[2] End 137,985,985 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in liver right lobe of liver skin of thigh renal cortex body of pancreas small intestine human kidney uterine tube rectum lower lobe of lung Top expressed in liver left lobe of liver embryo islet of Langerhans sexually immature organism epithelium of stomach spermatid lumbar subsegment of spinal cord thymus ureter More reference expression data BioGPS n/a
Gene ontology Molecular function serine-type endopeptidase inhibitor activity Cellular component extracellular exosome extracellular region extracellular space Biological process thyroid hormone transport negative regulation of endopeptidase activity Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 6906 331535 Ensembl ENSG00000123561 ENSMUSG00000031271 UniProt P05543 P61939 RefSeq (mRNA) NM_000354 NM_177920 NM_001382371 NM_001382372 RefSeq (protein) NP_000345 NP_808588 NP_001369300 NP_001369301 Location (UCSC) Chr X: 106.03 – 106.04 Mb Chr X: 137.98 – 137.99 Mb PubMed search [3] [4]
Wikidata
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Thyroxine-binding globulin (TBG) is a globulin protein that in humans is encoded by the SERPINA7 gene. TBG binds thyroid hormones in circulation. It is one of three transport proteins (along with transthyretin and serum albumin) responsible for carrying the thyroid hormones thyroxine (T₄) and triiodothyronine (T₃) in the bloodstream. Of these three proteins, TBG has the highest affinity for T₄ and T₃ but is present in the lowest concentration relative to transthyretin and albumin, which also bind T3 and T4 in circulation. Despite its low concentration, TBG carries the majority of T₄ in the blood plasma. Due to the very low concentration of T₄ and T₃ in the blood, TBG is rarely more than 25% saturated with its ligand. Unlike transthyretin and albumin, TBG has a single binding site for T₄/T₃. TBG is synthesized primarily in the liver as a 54-kDa protein. In terms of genomics, TBG is a serpin; however, it has no inhibitory function like many other members of this class of proteins.